class_docstr: Widget for proportionally dividing its internal area into a grid.
  
  This widget will automatically set the position and size of child widgets
  according to provided constraints.
  
  Parameters
  ----------
  spacing : int
      Spacing between widgets.
  **kwargs : dict
      Keyword arguments to pass to `Widget`.
code: def _add_gridding_height_constraints(solver, height_grid):
      # access heights of one "y"
      for hs in height_grid.T:
          for h in hs[1:]:
              solver.addConstraint(hs[0] == h)
  
imports: from __future__ import division
  import numpy
  from vispy.geometry import Rect
  from .widget import Widget
  from .viewbox import ViewBox
  from kiwisolver import Solver, Variable, UnsatisfiableConstraint
label_desc: Use image node_id 16 for calling the Grid obj's underlying member method code with example usage: obj._add_gridding_height_constraints(solver, height_grid) without return types